At present, chemical sensors and electronic nose technology lack the capability of operating at sub-10 nW or nearly-zero power, which limits their distribution over a large area due to limited lifetime during battery operation. Existing chemical sensors and electronic nose technology can be categorized into four main groups, depending on their working principles: conductivity, piezoelectric, optical and field-effect-transistor (FET) sensors. FET sensors operate based on threshold voltage changes that are caused by the interaction of a gate material with certain gases, resulting in changes in work functions. Such work function changes occur due to polarization of the gate material surface and interface with catalysts (e.g. metal oxides) by target gases. To enhance such interaction and thus sensitivity, these sensors preferably operate at an elevated temperature between 50° C. and 170° C., which is not appropriate for some low-power applications. Optical sensors utilize a coating of fluorescence dyes around an optical fiber and measure the optical property changes, such as wavelength shifts. However, optical sensors typically require a continuously-power-consuming scheme of light sources and detectors, making the system too complex and inappropriate for many low-power applications. Piezoelectric sensors, such as surface acoustic wave (SAW) and quartz crystal microbalance (QCM) sensors, measure the shifts in frequency of acoustic waves caused by interaction with or mass of gas molecules that are captured in a gas sensitive membrane. To produce high-frequency (>1 MHz) vibration of the device, piezoelectric sensors inherently require high power consumption of greater than 100 μW. Conductivity sensors produce changes in conductance by interaction with a gas and a gas sensitive membrane and are further categorized into three groups, depending on the membrane material types: polymer composites (non-conductive), conducting polymers and metal oxides. Among these materials, metal oxides require high temperature to operate as gas sensors, typically 200° C. to 500° C., thus requiring high-power consumption. Both non-conductive and conductive polymers operate at room temperature and do not need an integrated heater or high power consumption. However, their ‘off-current’ is non-trivial, typically above 1 μA considering their resistance values between 1 kΩ and 1000 kΩ at an operation voltage of 1.0 V, which results in power consumption of greater than 1 μW. Most recent percolation-based chemical sensors operate in liquid with non-trivial off-power consumption of greater than 1 μW. Additionally these sensors rely on pattern recognition electronics to achieve target selectivity, which further precludes nearly zero-power operation, which is not appropriate for extended lifetime from a battery. In short, existing chemical sensors and electronic nose technology have not simultaneously achieved chemical selectivity and ultra-low power consumption with long battery lifetime.